Electrical connectors generally speaking have conventionally comprised housings of dielectric material, usually plastic, having passageways within which are disposed electrical contacts each extending from a first contact section exposed along one face of the housing to a second contact section exposed along another face of the housing for electrical connection with corresponding contacts of first and second electrical articles, which articles may be, for example, another connector, or a circuit board, or an electrical cable, or even an electronic component. Where the article is a circuit board, the contact sections may be pins or posts which are inserted through holes of the board which are plated with conductive material joined to circuits of the board. One type of post is adapted to be soldered within the hole or to plating material around the hole entrance.
Another type of pin or post which forms an electrical connection to a circuit of a circuit board without the need for solder, accomplishes the mechanical connection and the electrical connection by means of a compliant spring portion which is compressed upon insertion into a plated through-hole of smaller diameter. A reference may be had to U.S. Pat. No. 4,186,982 granted Feb. 5, 1980 for a teaching of one type of compliant pin construction. A pin so made and dimensioned has been formed to provide an excellent elevational interface as well as resisting axial movement and thus being self-retaining within a cylindrical hole or cavity through a strong interference fit. Such compliant spring portions of contacts are defined by integral compressible spring elements which upon insertion are compressed by the side walls of the through hole or cavity.
It has not been considered desirable to utilize an interference fit for retention of contacts in cavities of molded plastic housings, especially where the interference fit establishes a retention force of from at least eight pounds up to about twenty-five pounds such as the levels for use in defining mechanical retention and electrical connection of contacts with circuit boards. During in-service use, plastic material generally would be expected to relax under such continued interference fit, and with such relaxation of material surrounding the force fit portions of the contacts, the interference fit would be considered unreliable for assured retention. Even with compliant spring contacts, such relaxation would result in normal forces lower than those considered satisfactory for assured, continuous gas-tight electrical connection, even though the contact may continue to be mechanically retained in the hole.
With the advent of circuit elements requiring three-dimensional structure for a variety of purposes where circuits are defined on articles of plastic material molded to define the three-dimensional structure, it would be desirable to provide such articles with contacts secured thereto to facilitate interconnection with other electrical articles.
It would be further desirable to provide for securing such contacts to such articles without requiring retention clips or other such fastening devices, and to establish the continued assurance of such retention upon the contacts being subjected to stresses from the interconnection with other electrical articles.
It would be an additionally desirable to provide for electrical connection of the contacts to circuits of the article without requiring solder or additional discrete conductive elements, since soldering is not desirable with connector elements molded of platable plastic since necessary temperatures therefor are detrimental to plastic materials, and cleaning of flux following soldering subjects the plastic to intolerable chemical attack, even those certain platable plastics which are useful with high temperature applications.
Further, it would be also desirable to provide a system for retention and electrical connection of the contacts to the article irrespective of the contact having a pin contact section or a socket contact section or other type of contact section for electrical interconnection with other electrical articles.